The long-term objective of this project is to gain a sufficient knowledge of the ecology of arboviruses for development of effective strategies to control those arboviral diseases that are of public health and veterinary importance in North America. Six areas of research are proposed currently to attain this objective: laboratory studies to elucidate instrinsic factors and mechanisms that control the competence of selected mosquito species to vector arboviruses that cause epidemics; controlled laboratory studies to determine the effect of temperature on the extrinsic incubation of arboviruses in their mosquito vectors and parallel field studies to evaluate the role of temperature as an environmental factor that influences the seasonal and yearly patterns of western equine encephalomyelitis and St. Louis encephalitis viruses; in-depth field studies on the ecology of WEE virus and its vectors in rural agricultural and riparian/marshland habitats in Kern County, California to identify basic foci of viral transmission and patterns of dissemination from such foci; study of alternative hypotheses to explain the overwintering of 6 enzootic arboviruses in their arthropod vectors and vertebrate hosts in Kern County, California; to develop statistical-epidemiological models that will integrate the variables that control mosquito population growth and associated arboviral transmission cycles including the impact of alternative strategies for control of vector populations; and to summarize research accomplishments during the past 40 years in the form of a monograph on "The Epidemiology of the Arthropod-borne Viruses in California, 1943-1984."